Arrangement in air blast circuit breakers



April 14, 1953 H. FORWALD 2,635,159

ARRANGEMENT IN AIR BLAST CIRCUIT BREAKERS Filed Aug. 4, 1949 INVENTOR fm/(alv Fain 44D.

ATTORNEY Patented Apr. 14, 1953 ARRANGEMENT IN AIR BLAST CIRCUIT BREAKERS Haakon Forwald, Valhalla, Sweden, assignor to Allmanna Svenska Elektriska Aktiebolaget, Vasteras, Sweden, a Swedish corporation Application August 4, 1949, Serial No. 108,521 In Sweden August 9, 1948 3 Claims. 1

In compressed air circuit breakers it has been proposed to restrict the delivery of compressed air to the breaking gap or breaking gaps immediately after the arc has extinguished but to allow so much compressed air to pass on to the arc gap that a reignition of the arc is prevented. The present invention relates to such circuit breakers but provides an arrangement wherein the delivery of compressed air to the circuit breaker takes place over a plurality of parallel-connected air blast valves, which, when the circuit breaker is to be opened, are opened simultaneously and allow the compressed air from the air container to reach the breaking gaps, but, after the extinguishing of the are or arcs, said valves are immediatel closed with the exception of one of the valves, which remains opened and allows so much air to flow to the arcing gap that a reignition of the arc is prevented. The valves may in already known manner be operated electromagnetically but may of course also be operated in any other suitable manner.

On the accompanying drawing one form of the invention is schematically shown. On the drawing 1 designates an insulator of one of the poles of the circuit breaker and 2 is a casing arranged on the insulator for operation of the disconnecting switch arm. 4, which is journalled in said casing 2. 3 designates the extinguishing chamber containing the contact pair of the circuit breaker. The disconnecting switch arm A is intended to engage in the stationary disconnecting switch contact 6, which is attached on the upper end of the insulator 5. The insulators l and 5 are mounted on the common bottom plate l.

Compressed air is delivered to the circuit breaker from the compressed air container 8 over three parallel-connected valves 9, which are in com.- munication with the container 8 over a pipe line I l, and further the valves 2 are also in communication with the circuit breaker over an air blast line I 8. The valves 9 are operated by solenoids I2 and i3 fed from an operating circuit i l. In the circuit is a contact [5 actuated by an operating piston It, which is actuated by compressed air from a container ll, which is in turn filled with compressed air over the pipe line it from the pipe line it as soon as the valves 9 are opened.

The arrangement so operates that, when opening the circuit breaker current is delivered to the solenoids l2 and i3. When compressed air flows to the circuit breaker the air container H is also filled with air from the pipe line l8 and thus the piston IS with a certain delay will open the contact l5 so that the current to the two solenoids I2 is interrupted, whereas the solenoid 13 still receives current. The two lower valves 9 will therefore be closed, while the uppermost valve 9 remains opened.

I claim as my invention:

1. An arrangement in compressed air circuit breakers, comprising at least two parallel connected air blast valves supplying compressed air to the breaker gaps of the circuit breaker, means supplying air to said valves, and means for closing at least one of said valves while at least one other valve remains open after the arc in the circuit breaker is definitely extinguished and the disconnecting switch is opened.

2. An arrangement in compressed air circuit breakers, comprising at least two parallel con nected air blast valves supplying compressed air to the circuit breaker, means suppyling air to said valves, electromagnetic means for the operation of said valves, a pneumatic device for the control of the electromagnetic operating means for at least one of said valves, and a pipe line from the outlet side of said valves supplying actuating air to said pneumatic device.

3. An arrangement in compressed air circuit breakers, comprising at least three parallel connected air iblast valves supplying compressed air to the breaker gaps of the circuit breaker, means supplying air to said valves, electromagnetic means for operating said valves, including a circuit common to the said electromagnetic means for operating said valves, a pneumatic device for opening a branch of said circuit to close at least two of said valves, and a pipe line from the outlet side of said valves supplying air to said pneumatic device to open said circuit branch after a time delay sufficient for the extinction of the arc in the circuit breaker.

HAAKON FORWALD.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,226,856 Gunter Dec. 31, 1940 2,331,441 Thommen et a1 Oct. 12, 1943 FOREIGN PATENTS Number Country Date 307,311 Great Britain Feb. 28, 1929 

